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Chapter 1. Creating a Red Hat High-Availability Cluster with Pacemaker

This chapter describes the procedure for creating a Red Hat High Availability two-node cluster using pcs. After you have created a cluster, you can configure the resources and resource groups that you require.
Configuring the cluster provided in this chapter requires that your system include the following components:
  • 2 nodes, which will be used to create the cluster. In this example, the nodes used are z1.example.com and z2.example.com.
  • Network switches for the private network, required for communication among the cluster nodes and other cluster hardware such as network power switches and Fibre Channel switches.
  • A power fencing device for each node of the cluster. This example uses two ports of the APC power switch with a host name of zapc.example.com.
This chapter is divided into three sections.

1.1. Cluster Software Installation

The procedure for installing and configuring a cluster is as follows.
  1. On each node in the cluster, install the Red Hat High Availability Add-On software packages along with all available fence agents from the High Availability channel.
    # yum install pcs pacemaker fence-agents-all
  2. If you are running the firewalld daemon, execute the following commands to enable the ports that are required by the Red Hat High Availability Add-On.

    Note

    You can determine whether the firewalld daemon is installed on your system with the rpm -q firewalld command. If the firewalld daemon is installed, you can determine whether it is running with the firewall-cmd --state command.
    # firewall-cmd --permanent --add-service=high-availability
    # firewall-cmd --add-service=high-availability
  3. In order to use pcs to configure the cluster and communicate among the nodes, you must set a password on each node for the user ID hacluster, which is the pcs administration account. It is recommended that the password for user hacluster be the same on each node.
    # passwd hacluster
    Changing password for user hacluster.
    New password:
    Retype new password:
    passwd: all authentication tokens updated successfully.
    
  4. Before the cluster can be configured, the pcsd daemon must be started and enabled to boot on startup on each node. This daemon works with the pcs command to manage configuration across the nodes in the cluster.
    On each node in the cluster, execute the following commands to start the pcsd service and to enable pcsd at system start.
    # systemctl start pcsd.service
    # systemctl enable pcsd.service
  5. Authenticate the pcs user hacluster for each node in the cluster on the node from which you will be running pcs.
    The following command authenticates user hacluster on z1.example.com for both of the nodes in the example two-node cluster, z1.example.com and z2.example.com.
    [root@z1 ~]# pcs cluster auth z1.example.com z2.example.com
    Username: hacluster
    Password:
    z1.example.com: Authorized
    z2.example.com: Authorized